Characterization of 3α-acetyl-11-keto-α-boswellic acid, a pentacyclic triterpenoid inducing apoptosis in vitro and in vivo

3 alpha-Acetyl-11-keto-alpha-boswellic acid (3 alpha-acetoxy-11-oxo-olean-12-en-24-oic acid, 1) was synthesized by a radical-type reaction using bromine and 3 alpha-acetyl-alpha-boswellic acid isolated from the oleo-gum-resin of Boswellia carterii. 1D and 2D NMR (COSY, HMBC, ROESY) at 500 MHz were used for shift assignments and structure verification. The compound investigated is present in a herbal preparation extracted from Boswellia serrata oleo-gumresin, it inhibits the growth of chemotherapy-resistant human PC-3 prostate cancer cells in vitro and induces apoptosis as shown by activation of caspase 3 and the induction of DNA fragmentation. In addition, compound 1 is active in vivo as shown by inhibition of proliferation and induction of apoptosis in PC-3 prostate cancer cells xenotransplanted onto the chick chorioallantoic membrane.